February 2015

Everything you want to know about the jet stream

...but are afraid to ask.

Skeptical Science contributor John Mason has outdone himself this time - which says a lot after his great pieces on Arctic methane and other subjects - by writing a comprehensive article about the jet stream, what it is, what it does and why that is important. Here's the introduction and table of contents, but I'd advise everyone to go read the whole thing over at Skeptical Science:

A Rough Guide to the Jet Stream: what it is, how it works and how it is responding to enhanced Arctic warming

Posted on 22 May 2013 by John Mason

Barely
a week goes by these days in the Northern Hemisphere without the jet
stream being mentioned in the news, but rarely do such news items
explain in detail what it is and why it is important. As a severe
weather photographer this past 10+ years, an activity which requires
successful DIY forecasting, I've had to develop an appreciation into
what makes it tick. This post, then, is a start-from-scratch primer
based on that knowledge plus some valuable assistance from academia into
where the current research is heading. Because of its length and
breadth of coverage, I've broken it up into bookmarked sections for easy
reference: to come back here click on 'back to contents' in each
instance.

The melting of the Polar ice and the changes it brings to the jet stream and the weather in Europe, Russia, China and the USA are, I believe, potentially the the fastest and most threatening tipping point there is. If the ice goes the weather is affected the same autumn and this leads to crop failure. My cousins are farmers in the UK and they are having a tough time now and it has hardly started,
I live in NZ now and we are affected less than most countries but we are not immune.http://www.climateoutcome.kiwi.nz/

John provides an excellent recitation of the conventional wisdom of modern weather theory. However, we know that modern weather theory does not always do a perfect job of predicting the weather. Weathermen claim natural variation, but there may be deeper reasons. For a very long time I have felt the conventional wisdom failed to adequately account for water vapor. See:

The jet stream is wind. If you want to understand it, you have to (also)think about water vapor. Failure to fully address water vapor is another reason I am not happy with climate models.

This paper has been disparaged as having too much math. Weather (wind) is the internal work of a thermodynamic engine (Earth). And, math is the best language we have to describe thermodynamic processes.

In a former life, I taught Weather for the FAA Mandated annual Flight Dispatch Recurrent Training at a major airline. This is one of, if not the best overview of the jetstream and associated features I've ever seen, A little too advanced for the average Dispatcher - but as complete as any one of them would need.

If anybody would like a primer on the Coriolis force (mentioned in this piece and often misunderstood), there was an excellent and relatively short three part series in the journal 'Weather' in 2000 by Anders Persson. The links below provide links to the three free to download pdfs of the series, collectively titled 'Back to Basics.'Part OnePart TwoPart Three

I have added loads of images to the Petermann Fjord Map, primarily the shore line of Hall Land (north eastern shore).
Most important localities from Hall´s Grave (in Nares Strait) to Kap Egedesminde (a the top of Petermann Glacier) are covered, and more will come, I recognize most of the images are from 1984, but as the skeptics tells us it hasn't changed much ;), newer images is supplied by Andreas Muenchow who visited the area in 2012.
Some unofficial names are supplied by me, like First One To The Left Glacier, The Parallel Glaciers, Sankt Peders Vej Glacier, Hellerupvej Glacier(named after some streets in Hellerup, a district in the suburb of Copenhagen, and since both glaciers are located in Hellerup Land I find both names appropriate), Between A Rock And A Hard Place Glacier.

I also like to draw your attention to the inland calving that happened in 1984 or probably earlier, it is called Inland Calvin Site on the map and it is located between the tops of Steensby Glacier and Ryder Glacier in N. P. Johansen Land. It is an impressive piece of demolition work, to say it at least.

Thanks for the Coriolis primer, Phil! I was aware of the insufficiency of the "Hadleian" explanation (which I learned decades ago from a prominent Canadian meteorologist, then my father-in-law), but didn't have a more sufficient replacement.